In this paper, we propose a new theoretical scheme for quantum secure direct
communication (QSDC) with user authentication. Different from the previous QSDC
protocols, the present protocol uses only one orthogonal basis of single-qubit
states to encode the secret message. Moreover, this is a one-time and one-way
communication protocol, which uses qubits prepared in a randomly chosen
arbitrary basis, to transmit the secret message. We discuss the security of the
proposed protocol against some common attacks and show that no eaves-dropper
can get any information from the quantum and classical channels. We have also
studied the performance of this protocol under realistic device noise. We have
executed the protocol in IBMQ Armonk device and proposed a repetition code
based protection scheme that requires minimal overhead.

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